The present invention relates generally to digital communication networks, and more specifically, to methods and systems for efficiently transporting Fibre Channel client data, among other protocols, over a SONET/SDH network path.
SONET/SDH and optical fiber have emerged as significant technologies for building large scale, high speed, Internet Protocol (IP) based networks. SONET, an acronym for Synchronous Optical Network, and SDH, an acronym for Synchronous Digital Hierarchy, are a set of related standards for synchronous data transmission over fiber optic networks. SONET/SDH is currently used in wide area networks (WAN) and metropolitan area networks (MAN). A SONET system consists of switches, multiplexers, and repeaters, all connected by fiber. The connection between a source and destination is called a path.
One network architecture for the network interconnection of computer devices is Fibre Channel, the core standard of which is described in ANSI (American National Standards Institute) X3.230-1994. Arising out of data storage requirements, Fibre Channel currently provides for bi-directional gigabit-per-second transport over communication networks in Fibre Channel frames that consist of standardized sets of bits used to carry data over the network system. Fibre Channel links are limited to no more than 10 kilometers.
New standards and protocols have emerged to combine the advantages of the SONET/SDH and Fibre Channel technologies. For example, it is sometimes desirable to link two SANs (Storage Area Networks), which operate with Fibre Channel protocol, over a MAN (Metropolitan Area Network), or even a WAN (Wide Area Network), which typically operates under SONET or SDH standards. This extension of Fibre Channel from 100 kilometers to over several hundred, or even thousand, kilometers, is made by mapping Fibre Channel ports to a SONET/SDH path for transport across a SONET/SDH network. One way to perform this function is to encapsulate Fibre Channel client data frames into transparent Generic Framing Protocol (GFP-T) frames and then map the GFP-T frames into SONET/SDH frames for transport across the SONET/SDH network.
Fibre Channel systems have two types of flow control: 1) end-to-end, and 2) buffer-to-buffer credit. In both types of flow control, two ports report to each other how many frames is available at that port's buffer to receive Fibre Channel frames from the other port. In end-to-end flow control, the source and destination ports are the two ports and the ports signal each other the reception of a transmitted frame by an ACK Link Control frame. In buffer-to-buffer credit, the two ports on opposite sides of a link are the two ports and the ports communicate the reception of a transmitted frame with an R_Rdy Primitive signal. But flow control is within the Fibre Channel network and is based on counting Fibre Channel frames which can vary.
In the present invention, flow control is provided across SONET/SDH transport networks which connected frame-based protocol networks, such as Fibre Channel and gigabit Ethernet. Furthermore, flow control is based on bytes to better utilize the size of the buffer receiving GFP-encapsulation frames.